As used herein, the term “user equipment” (alternatively “UE”) might in some cases refer to mobile devices such as mobile telephones, personal digital assistants, handheld or laptop computers, and similar devices that have telecommunications capabilities. Such a UE might include a device and its associated removable memory module, such as but not limited to a Universal Integrated Circuit Card (UICC) that includes a Subscriber Identity Module (SIM) application, a Universal Subscriber Identity Module (USIM) application, or a Removable User Identity Module (R-UIM) application. Alternatively, such a UE might include the device itself without such a module. In other cases, the term “UE” might refer to devices that have similar capabilities but that are not transportable, such as desktop computers, set-top boxes, or network appliances. The term “UE” can also refer to any hardware or software component that can terminate a communication session for a user. Also, the terms “user equipment,” “UE,” “user agent,” “UA,” “user device,” and “mobile device” might be used synonymously herein.
As telecommunications technology has evolved, more advanced network access equipment has been introduced that can provide services that were not possible previously. This network access equipment might include systems and devices that are improvements of the equivalent equipment in a traditional wireless telecommunications system. Such advanced or next generation equipment may be included in evolving wireless communications standards, such as long-term evolution (LTE). For example, an LTE system might include an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) node B (eNB), a wireless access point, or a similar component rather than a traditional base station. Any such component will be referred to herein as an eNB, but it should be understood that such a component is not necessarily an eNB. Such a component may also be referred to herein as an access node or a network element.
Any set of cells that includes one or more cells with a smaller coverage area than the typical coverage area of a traditional eNB may be referred to herein as a small cell deployment. A cell with the relatively large coverage area provided by a traditional eNB may be referred to herein as a macro cell. A cell with a relatively smaller coverage area than a macro cell may be referred to herein as a small cell, a pico cell, or a femto cell. Alternatively or additionally, a macro cell may be considered a high-power cell, and a small cell may be considered a low-power cell. The access node in a macro cell may be referred to as a macro eNB or a macro node, and the access node in a small cell may be referred to as a small cell eNB, a pico eNB, or a femto eNB. When reference is made herein to an action being taken by a cell, it should be understood that the action may be taken by a component in the cell, such as an eNB.
LTE may be said to correspond to Third Generation Partnership Project (3GPP) Release 8 (Rel-8), Release 9 (Rel-9), and Release 10 (Rel-10), and possibly also to releases beyond Release 10, while LTE Advanced (LTE-A) may be said to correspond to Release 10, Release 11 (Rel-11), and possibly also to releases beyond Release 10 and Release 11. As used herein, the terms “legacy”, “legacy UE”, and the like might refer to signals, UEs, and/or other entities that comply with LTE Release 11 and/or earlier releases but do not comply with releases later than Release 11. The terms “advanced”, “advanced UE”, and the like might refer to signals, UEs, and/or other entities that comply with LTE Release 12 and/or later releases. While the discussion herein deals with LTE systems, the concepts are equally applicable to other wireless systems as well.